'''
常量
'''
# 清空控制台
CLEAR = "-c"
# 退出程序
QUIT = "-q"
# 帮助
HELP = "-h"
# 全匹配查询
ALL = "-a "
# 以该字符串开始
START = "-s "
# 以该字符串结束
END = "-e "
# 从注释里面查询
EXPLAIN = "-p "
# 命令开头
COMMAND_PREFIX = "-"
